pl: add debug_read

src/platform/root.zig

@@ -27,6 +27,11 @@ pub inline fn debug_write(c: u8) void {
     return impl.debug_write(c);
 }
 
+/// Read a single character from the debug console.
+pub inline fn debug_read() u8 {
+    return impl.debug_read();
+}
+
 /// Arm a one-shot timer to fire in `ns` nanoseconds.
 pub inline fn arm_timer(ns: u64) void {
     return impl.arm_timer(ns);